I think I found the answer...
First clue: While looking around the Puget Sound for ham clubs doing Field Day I came across the Island County Amateur Radio Club website. They had a photos page - Surprise! A tower photo of KWDB.
Photos
www.w7avm.org
Second clue: Like many listeners in the North Puget Sound, I listen to Rock 101 (CFMI) over-the-air as they don't stream to the US. When KWDB was off the air then CFMI becomes an easy catch. Tonight at 19:00 KWDB came back on the air - the announcer mentioned something about an AT&T tower crew working next door and was going to still be there for the next few days.
So, taking both clues you can look at the KWDB tower site and see it's surrounded by cell towers. Whenever tower climbers go on those adjacent cell towers the station has to signoff. I guess the radio station owner must be overly-cautious or does not want to tempt fate.